My heart goes really fast and all I have to do to make it go fast without working out is just think about it.... like 150 to 190bpm. I was told that adrenaline and cortisol get released when you fear and the flight fight mode is being activated by the mind which in turn speeds up the heart and a cycle begins. How come I fear my heart going fast then within seconds to a minute or so it actually does? I  didn't think I would have thought control over a heart. I can think or tell my heart to go 60bpm but it's not going to go and do what I say or think of. So is this just a part of a panic attack? I have been checked out left and right including stress test(s), holter monitors, thyroid and adrenals were checked and I my doctor also checked just about every blood test available. If I am ok...then why all the fast heart beats? My doctor gave me 25mg of Atenolol and 1.0mg of Xanax to calm myself down. Thank you for your time. ~ Tommy